A factory for producing the pesticide hexachlorocyclohexane (HCR) in its technical grade (mix of the alpha, beta, gamma, and delta isomers), that belonged to the former Institute of Malaria Sciences, then Ministry of Education and Health, located in the "Cidade dos Meninos", county of Duque de Caxias, State of Rio de Janeiro, was closed down in 1955. Part of its production and wastes - many tons this mix - were left behind on the site. The action of winds and rain as well as the movement of the local inhabitants - approximately 1,000 people, including 400 children, have caused the scaltering of this agent. Blood specimens from the inhabitants showed a high human contamination levels, with the highest concentration (beta isomers) being found in people living within a 100 meter radius of the ruin of the factory. Local soil and pasture samples taken at distances of less than 100 m from the ruin of the former factory showed HCH isomer concentrations of the order of thousands of ppb, thus providing evidence of high environmental contamination.